In many countries a typical method of facilitating terrorism involves attaching explosives, infiltrators or weapons to a vehicle's undercarriage. The vehicles then attempt to enter secure areas such as military bases, embassies and other government installations. Often, entry controllers are required to inspect the undercarriage of vehicles to detect such undesirable embellishments.
Conventional inspection systems include mirrors mounted on shafts to be extended under the vehicles and video cameras mounted on shafts with monitors attached to the entry controller's head gear or nearby monitoring stations having additional security personnel. Other systems use fixed cameras mounted on the underside of a ramp over which the vehicles pass. Some systems require the vehicle to stop in a prescribed location while motor driven cameras traverse the length of the vehicle. In each of the cases using cameras at least one inspector views each resulting image. There are also some patents covering like types of systems for determining what is traveling along a road.
U.S. Pat. No. 5,446,291, Method for Classifying Vehicles Passing a Predetermined Waypoint, to Becker et al., Aug. 29, 1995, uses a complex electronic sensor and processing system for military reconnaissance to measure speed, distance, and number of axles to classify vehicles to correlate to a database of military vehicles. An image is not taken of the undercarriage of the vehicles.
U.S. Pat. No. 5,750,069, Method and Apparatus for Discriminating Vehicle Types, to Lew et al., May 12, 1998, details a technique for identifying a vehicle's type by measuring the pressure imposed by a vehicle's tires on a contact board(s) in the roadway. The system measures the width of the tires, the distance between tires and the number of axles. An image is not taken of the undercarriage of the vehicles.
Often, automated inspection systems are degraded by distortion introduced in the detector(s) used to collect images. Distortion includes that produced by “contrasts” resultant from projections of electromagnetic energy, e.g., shadows, not necessarily visible, induced by light (or other electromagnetic energy) projected onto an irregular or contoured surface. This type of distortion is actually used as a beneficial consequence in preferred embodiments of the present invention. Processing of this “distorted” data after collection of suitable reflections of this energy at a pre-specified sampling rate, to include an optional FFT conversion of digital data and implementation of a simple algorithm, provides the “third dimension” absent in a conventional analog or digital representation of the surface. As an example of one application of the present invention, a suite of simple commercial-off-the-shelf (COTS) hardware may be used to determine a 3-D undercarriage configuration as a vehicle passes over the illumination/detection portion of the present invention that is embedded in or below the roadway.